Voltage-regulator for alternating-current generators.



PATENTED MAR. 5, 1967.

E. E. KELLER. VOLTAGE REGULATOR POR ALTERNATING CURRENT GEN RATORS.

APPLICATION FILED OUT. 22. 1906.

www www VUM' FREDERICK R. KELLER, CF LANCASTER, PENNSYLVANIA.

VOLTAGE-REGULATOR FOR LTERNATiNG-CURRENT GENERATORS.

Specification of Letters Patent.

Patented Mareh, 1907.

Application filed October 22. 1906. Seriai No. 340,006.

fifo all, 'w22/ont it' may con/cern:

Be it known that I, FREDERICK R. KELLER, citizen of the TUnited States, residing in Lancaster, Pennsylvania, have invented. eertain Improvements in Voltage-Regulators for Alternating-Current Generators, oi 'which shall be automatically varied to maintain the voltage of said generator substantially constant in spite ci' the drop due to its own impedance under load and of variation in the driving speed of the generator or exciter.

These objects, as well as other advantageous ends, I secure as hereinafter set forth, reference being had to the accompanying drawing, in which the iigure is a diagrammatic view illustrating the preferred arrangement of apparatus and connections therefor constitutingmy improved system of apparatus.

In the above drawing, Arepresents an alternating-current generator whose voltage it is d sired to regulate, it having an armature o, and a field-winding a and. being designed to supply alternating current to current-mains a2, a3, and a4.

For energizing the held-winding a I provide an exciter B, which in the present in` stance is a machine of the direct-current type having an armature b and a field-winding b. The machine B as a whole is so signed that under operating conditions its iield is unsaturated, and consequently relatively small variations in its iield-current will result in relatively large changes in the vol-- tage of the current generated.

For regulating the voltage oi the exciter B, and consequently the voltage of the alternator A, I provide a rotary converter C, having its alternating-current end connected to the current-mains a2, a3, and at through suitablydesigned potential-transformers l, 2, and 3, while its direct current end is connected in series with the field-Winding b oi the exciter. Also connected in series with the exciteriield is a storage battery D, so arranged that under normal operating conditions its voltage balances or neutralizes, as nearly as may be, the voltage of the current generated by the rotaryconverter C. The connections of the battery and rotary with the exciter. are such that current generated by the rotary tends to oppose the field-current of the exciter, and while, if desired, this circuit may contain merely the exciter B, the battery D, and the rotary C, I preferably also insert therein a second rotary converter E, having its alternating-current end supplied with current from a transformer 4, whose primary winding is in series with one of the currentmains. Its direct-current end is so connected in the circuit that the current generated by it tends to flow in the same direction as that generated by the exciter B and by the battery D, though it opposes the current generated by the rotary C. .This rotary-E is preferably driven-from the shaft oi the rotary C and may be of what is known as the inductor type.

Under normal operating conditions, with a full load on the generator A, the battery D and the rotary C are se designed and proportioned as to substantially neutralize each other, the current flowing through the fieldwinding 5 of the exciter B being that due to the voltage generated by the exciter plus that due to a smallvoltage generated by the rotary E. If now from any cause the voltage at the terminals oi the generator A should tall, there would be a corresponding fall in the voltage of the alternating current supplied to the rotary C and a similar i'all in the voltage ofthe direct current generated by it. As a consequence the battery-voltage would be in excess of that generated by the rotary C and an increased current -'would iiow through the 'held-v. inding i the 'exciter' In view of the unsaturated co'ndition the field of this machine there would at once be a relatively large increase in the voltage ci the current generated by it, so that the iield of the alternator A would be immediately strengthened and itsvoltage raised to an extent to compensate for the drop. Similarly, if for IOD any reason thevoltage oi' the alternator should increase this would result in a cutting down oi the field-current of the exciter and a consequent relatively large falling oii in the magnetiZing-current of the main alternator, with a resulting lowering in` ts voltage substantially equal tothe previous increase.

The rotary E serves as a compounding or over-compounding device, for in the event of a heavy load being put upon the alternator A it is .obvious that'the voltage at the alternating-current terminals of said rotary would be increased. Since this results in an increase vin the voltage of the direct current generated, there would be a corresponding increase in thev current flowing through the excitereield circuit and a resulting strengthening .of the Vfield of the alternator A, with the desired compounding .effect in maintaining constantthe voltage at s orne distant point in the circuit supplied by the mains 0.2, a?, and o4.

. tis .of course obvious thatthe use of the battery D isnot'a necessity, since the rotary C andthe ,exciterB could be so designed as to secure the desired `eiect withoutits use. I

prefer, however, to use thel battery .or some equivalent source of constant voltage, for the reason that by so doing the .effect of variations in thevoltege of the. direct-.current .end of :the rotary() s magnified and the .System as a .whole is rendered incre sensitive 4to changes in the voltage of the alternator A. .lit .s vfurther tobe noted lthat the .compoundngrotary E may be ,altogether omitted-if it be desired'to dispense .with its partouler function, though .under operating Conditions I preferably employ it, ,as shown. If-it .be desired .to temporarily. .out said .letterrotay Eout .of circuit, this meyroedone by shortcircuiting the winding'ofthe transformer 4 luy-means .cfa Switches-f.. v

I ,claim as my .inventions- 1'. The .combnetiongwith ,an alternatingcurrent .genera-.tor and tseXC-ter, of. regulatingnieans consisting of ,a rotary converter,

'having .its elteroetnU-current end Supplied ,trein said generator audits directcurrent end .connected to .oppose the. current gener-f' .ated by theexeter, with a source ofconstant voltage connected in series with the direc-tcurrent end of therotary converter to .o p- -pose the current generated thereby, substantially as described 2. The combination .with .en alternatngcurrent generator and its exciter, of arotary converter having its alternating-current end supplied with current from saidgenerator .and its .direct-current end connected ,in series with the held-Winding of the exciter, witha storage battery also connected in series with the heldwinding and so arranged that its voltage under normal conditions substantiallyequa'lsand neutralizes that of the direct-current end 0i' the rotary converter, substantially as described.

scenic 3. The combination with an alternatingcurrent generator and its exciter, of two rotary converters having their alternating-current ends respectively supplied from the generator and 'from a 'series-transformer connected in the line, the direct-current ends of said rotaries being .connected in series with .the held-winding. of the exciter, substantially as described. 4, The combination with an alternatingcurrent-generator and its exciter, of two rotary converters having their alternatingcurrent ends suppliedfiroin said generator, the direct-current ends of said rotariesbeing connected in series with the 'field-winding of the exciter, the latter of the rotaries being connected to generate a current r'lowing in the saine V( lirection as that generated by. the exciter and to oppose that generated by the other rotary, substantially as described.

5. The combination with an alternatingcurrent generator and its exciter, of two rotaries having their alternating-current ends supplied from said generator, the direct-current ends of said rotaries being connected in series with the fieldwinding ofthe exciter, the rotor of one of said two rotaries being driven Jfrom the rotor of the other rotary, substantially as described 6. The combination with an alternatingv( Eurltjlllt generator' and its exciter, of two rotary converters su plied with current from said generator 4an having their direct-current ends connected to the exciter, the rotor of one of the rotaries being driven from the rotor of. the other, substantially as described.

. 7. The combination of a pairof rotary converters having their direct-current ends connected to oppose each other, a storage battery'connected in series with the direct-current ends of said rotaries, andan exciter hav- FREDERICK R. KELLER.

Witnesses:

FoRREsT J. AULT,

EDW. R. Hnirsnu IOO TIO 

